1. Field of the Invention
The present invention relates to a stirling-cycle refrigerator (hereinafter a "stirling refrigerator"), and more particularly to a pump for circulating a heat-transferring medium.
2. Prior Art
In general, a stirling refrigerator is an appliance to produce refrigerating capacity by making a working fluid such as helium or hydrogen repeatedly experience two isothermal processes and two isochoric processes, and various types of stirling refrigerators have been introduced so far.
Japanese Patent Laid-Open No. 5-126427, published on May 21, 1993, discloses a conventional stirling refrigerator.
That conventional stirling refrigerator, as shown in FIG. 1, has a system 18' including a compression chamber 11', a first connecting tube 12', a radiator 13', a second connecting tube 14', a cold accumulator 15', a third connecting tube 16', and an expansion chamber 17'. The system 18' contains a working fluid and further includes a fluid-pressure-and-velocity-controller 29' for controlling the pressure and velocity of the working fluid.
The fluid-pressure-and-velocity-controller 29' includes a branch tube 26' one end of which is connected to the third connecting tube 16', an orifice 27' connected in series to the other end of the branch tube 26', and a backup tank 28'.
In the conventional stirling refrigerator described above, the fluid-pressure and-velocity-controller 29' of the system 18' is operated further efficiently in the range of ultra-low temperature and maintains the pressure and velocity difference of the working fluid nearly the same under an ultra-low temperature as under normal or low temperature. Therefore, the fluid-pressure-and-velocity-controller 29' enables an efficient operation of the stirling refrigerator even in the range of ultra-low temperature, thereby improving the refrigerating efficiency.
However, the conventional stirling refrigerator as described above has an disadvantage in that the driving devices 21, and 24', which are respectively installed at the compression chamber 11' and the expansion chamber 17', cause too much vibration and loud noise when they are operated, thereby diminishing the quality of the stirling refrigerator.
Further, the cold accumulator 15' and the radiator 13' respectively require a heat-transferring medium and pumping means for circulating the heat-transferring medium, thereby inevitably increasing the power consumption, as well as enlarging the refrigerator.
That is, the conventional stirling refrigerator has various problems in that the vibration and noise generated by the driving devices diminish the quality of the refrigerator, the power consumption is increased, and the size of the refrigerator is enlarged because separate pumping means for circulating heat transferring medium are required.